Fixed point temperature sensing in combination with a rate of rise detector is already known, as exemplified in U.S. Pat. No. 4,651,140 which issued Mar. 17, 1987. According to this structure, a fusable metal having a specified melting point is used to maintain a mechanical arrangement and upon reaching of the particular temperature, the mechanical arrangement is released, causing the device to operate. Once the fixed point temperature sensing device has been actuated, the entire detector must be replaced. Therefore, any testing of the device must be done in association with the rate of rise sensing mechanism which is resettable. Electronic fixed point temperature sensing devices are known and because of their electronic nature, can be tested and reset.
Smoke detectors have often proven popular and operate on a different principle, namely, the detection of smoke in the air which is an indication that a fire is present. In a complete monitoring system having a number of smoke detectors such as that manufactured and sold by Cerberus Pyrotronics, the system operates on a parallel circuit where each device draws a very low amperage and an alarm signal is indicated by a substantial drop in voltage between the two parallel lines. Although smoke detectors are desirable in certain applications, it would also be desirable to be able to substitute in an existing system a smoke detector device with a fixed point temperature detecting device in combination with a rate of rise sensing mechanism, which in certain applications is more advantageous. This requires the detecting device to be compatible with the operating characteristics of a smoke detecting system and the smoke detecting devices used therein.